First off, let me say, WOW, what a worthy adversary.
I came across one of these guys at the end of a Khazan Exploration mission, saving a bunch of weird looking things who built machinery from the Remans. I kill everything off and make my way to the last group. A Reman Guard Captain and 3 of his little guard buddies. Thinking this as just another pull, I go in guns blazing. Next thing I know, I'm on the floor, swarmed with this invisible purple guys. What the hell?
I've never come across a Reman Guard Captain before, so I didn't know what to expect. I'm not even sure how to fight them other than brute force. His little summons (purple invisible guys) go all over the place, and then usually focus on the science officer I have assigned to healing. Once he's down it's game over. And their attacks go right through his shields, so there's really no helping him.
So, plans, strategies, will I see more, I need details. I'm really dreading my next encounter with one, because these guys just **** me off. Fun, but insanely difficult, so I must not be doing something right.
For those unsure of what I mean by invisible purple guys, I took a screenshot.